In a shallow dish, whisk lemon juice, Worcestershire, mustard, 1 tablespoon olive oil, sugar, garlic, salt, and pepper.
Pierce steak all over with a fork; toss in marinade. Marinate 30 minutes, turning once.
In a cast-iron skillet, heat remaining tablespoon olive oil over high until smoking. Remove steak from marinade; cook until browned, 4 to 5 minutes per side for medium-rare. Rest, covered, 5 minutes.
In a saucepan, bring marinade to a boil; strain into serving dish.